diff --git a/src/threads/thread.c b/src/threads/thread.c
index 74ac41e..1fcbc01 100644
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -688,6 +688,7 @@ init_thread (struct thread *t, const char *name, int nice, int priority,
   t->recent_cpu = recent_cpu;
   t->priority = t->base_priority;
 
+  t->fd_counter = MINIMUM_USER_FD;
   t->exit_status = -1;
   list_init (&t->child_results);
 
diff --git a/src/threads/thread.h b/src/threads/thread.h
index 33a5485..c18500b 100644
--- a/src/threads/thread.h
+++ b/src/threads/thread.h
@@ -32,6 +32,9 @@ typedef int tid_t;
 #define NICE_DEFAULT 0 /* Default niceness. */
 #define NICE_MAX 20    /* Highest niceness. */
 
+/* File Descriptors. */
+#define MINIMUM_USER_FD 2 /* Minimum file descriptor for user programs. */
+
 /* A process result, synchronised between parent and child. */
 struct process_result
 {
@@ -137,7 +140,9 @@ struct thread
 #ifdef USERPROG
     /* Owned by userprog/process.c. */
     uint32_t *pagedir;                  /* Page directory. */
-    struct hash open_files;             /* Hash Table of FD -> Struct File */
+    unsigned int fd_counter;            /* File descriptor counter for thread's
+                                           open files. */
+    struct hash open_files;             /* Hash Table of FD -> Struct File. */
 #endif
 
     /* Owned by thread.c. */
diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index 1759bf1..015ebb7 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -16,8 +16,6 @@
 #define MAX_SYSCALL_ARGS 3
 #define EXIT_FAILURE -1
 
-static unsigned fd_counter = MIN_USER_FD;
-
 struct open_file
   {
     int fd;                     /* File Descriptor / Identifier */
@@ -224,7 +222,7 @@ syscall_open (const char *file)
     }
 
   /* Populate the above struct, with a unique FD and the current open file */
-  file_info->fd = fd_counter++;
+  file_info->fd = thread_current ()->fd_counter++;
   file_info->file = ptr;
 
   /* Add the new FD->file mapping to the hashtable for the current thread */
diff --git a/src/userprog/syscall.h b/src/userprog/syscall.h
index 681a8fb..b1ec52d 100644
--- a/src/userprog/syscall.h
+++ b/src/userprog/syscall.h
@@ -4,8 +4,6 @@
 #include <hash.h>
 #include "threads/synch.h"
 
-#define MIN_USER_FD 2
-
 typedef int pid_t;
 
 struct lock filesys_lock;